I just had the same thing done to my '94 C280, and luckily my mechanic doesn't mind if I hang out with him while he works on the car, so I got to watch the whole procedure. It didn't look that difficult, just a little time consuming. I think it took about 2.5 hours from start to finish. He had to remove the fan shroud and then the fan, and removing the fan seemed to be the trickiest part only because you have to be careful to not harm the radiator when loosening the nut that holds the fan it.

Its a good opportunity to replace the serpentine belt, since you'll have it off the car anyways. The part cost $280 Canadian, straight from the dealer, plus labour and coolant.

Jonathan